EDK: Remove MOJO_SYSTEM_IMPL_EXPORT, system_impl_export.h, etc.

mojo/edk/embedder/platform_channel_pair.h

Index: mojo/edk/embedder/platform_channel_pair.h
diff --git a/mojo/edk/embedder/platform_channel_pair.h b/mojo/edk/embedder/platform_channel_pair.h
index 01ebdcd52e37b3fd5312991addf7c41a89406870..5f44ef42672e435b7e863f5996560ac8a1b53705 100644
--- a/mojo/edk/embedder/platform_channel_pair.h
+++ b/mojo/edk/embedder/platform_channel_pair.h
@@ -7,7 +7,6 @@
 
 #include "base/process/launch.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
-#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace base {
@@ -41,7 +40,7 @@ using HandlePassingInformation = base::FileHandleMappingVector;
 // |PlatformChannel{Write,Writev}()| (from platform_channel_utils_posix.h)
 // instead of |write()|, |writev()|, etc. Otherwise, you have to worry about
 // platform differences in suppressing |SIGPIPE|.
-class MOJO_SYSTEM_IMPL_EXPORT PlatformChannelPair {
+class PlatformChannelPair {
  public:
   PlatformChannelPair();
   ~PlatformChannelPair();